L C Fuller1,2, R J Hay2,3. 1. Chelsea and Westminster Hospital NHS Foundation Trust, 369 Fulham Road, London, SW10 9NH, U.K. 2. International Foundation for Dermatology, Willan House, 4 Fitzroy Square, London, W1T 5HQ, U.K. 3. Department of Dermatology, King's College Hospital, Denmark Hill, Camberwell, London, SE5 9RS, U.K.